1. Field of the Invention
The present invention relates to the conversion of solar energy to electrical energy, and more particularly to portable carts having solar energy conversion features.
2. Description of Related Art
In the aftermath of severe storms, such as hurricanes and tornados, the power grid servicing homes and businesses in the affected area is often heavily damaged due to fallen utility poles and disconnected power lines. Such outages may last for several hours in some cases, or they may remain for weeks, depending on the severity of the damage and the availability of repair crews. When electrical power is lost after a hurricane, the suffering and inconvenience are often compounded by a lack of sufficient air conditioning, as well as loss of food within refrigerators and freezers within a matter of days. For these reasons, persons in affected areas have often resorted to gasoline or diesel powered generators to keep a variety of devices running, including fans, lights, refrigerators, and freezers, until conventional electrical power is restored.
However, gasoline and diesel generators have a number of distinct disadvantages. First, they require constant refueling at a time when petroleum-based fuels may be scarce or located far away. Second, some generators may require air permit or petroleum storage permits. Third, such generators are noisy due to their internal combustion engines, and they produce harmful carbon monoxide, making them unsuitable for use indoors or in poorly ventilated areas. Finally, to produce greater amounts of power, larger generators are required, further exacerbating the above problems due to their high fuel consumption.
In view of the problems with petroleum-based generators, photovoltaic solar panels have been used in a wide variety of situations. However, one challenge of using solar energy is that of providing a reasonably steady and continuous source of electricity for storage in batteries for use in powering appliances, lights, and other devices. For example, most renewable energy systems, such as solar and wind energy systems, are highly transient energy sources and exhibit strong variations in their energy outputs. Specifically, in the case of solar devices, high energy output is typically seen in the middle of the day during the summer months. Conversely, minimal energy output (or no output at all) is experienced during night time and during the winter months. Thus, they require proper means to store the energy produced in periods of low demand in order to stabilize the output when the demand is high.
Portability and remote operation of solar generation systems present several challenges, including the need to deliver a range of DC and AC voltages, frequencies and waveforms over widely divergent climate and weather conditions. Another challenge in the solar industry is that there is no standard size, shape and construction of solar modules. This variability typically has constrained users of solar modules to a single type or manufacturer of solar modules and limits opportunities to improve cost or performance for packaged systems. Moreover, the prior art devices were not adapted to readily receive multiple solar panels.
Compactness, stability and ease of assembly in the field are highly desirable for operation in remote locations. Prior art units, however, are often bulky or difficult to assemble. A design constraint for the cart assembly is that it must be adapted to hold storage devices, such as an array of batteries, which are typically much heavier when compared to the rest of the equipment. Prior systems were often unstable in the sense that they required the presence of a battery and the solar panel to remain in equilibrium. If the battery was removed and the panel was in place, often times the device would tip over, resulting in damage to both the panel as well as other components. Thus, it is important for a portable solar generator to incorporate a weight-balanced design that avoids these problems.
Accordingly, there is a need for a source of portable power that: (a) can be moved from location to location, (b) is not reliant on petroleum-based fuel, (c) does not cause or add to air pollution or noise pollution, (d) does not require environmental permitting, (e) remains structurally stable during removal and attachment of the solar panels and batteries; and (f) generates sufficient power for critical appliances, such as refrigerators, freezers, lights, and fans. Over the years, a number of devices have been developed to provide portable solar power, including U.S. Pat. No. 6,201,181 to Azzam; U.S. Pat. No. 6,396,239 to Benn; U.S. Pat. No. 6,974,904 to Azzam; U.S. Pat. No. 7,105,940 to Weesner; U.S. Pat. No. 7,492,120 to Benn; and U.S. Pat. No. 7,469,541 to Melton. While these devices may be suited to their specific applications, they do not provide the benefits achievable through use of the present invention.